Automatically Mount Encrypted Core Storage Volume (10.14.4+)

Prior to Mojave 10.14.4, macOS would automatically attempt to mount locked Core Storage volumes, and if the necessary password was found in the current user's keychain this would occur automatically.

I've taken advantage of this behaviour until now to allow me to have multiple encrypted volumes that are all mounted automatically by successfully logging in to a user account on my encrypted startup volume.

However, macOS no longer appears to be attempting to mount Core Storage volumes automatically, despite the necessary passwords being in either my user keychain, or the system keychain, forcing me to mount them manually with Disk Utility. This isn't ideal as it ties the volumes to the user account, meaning if I log out the volumes are locked again.

This behaviour differs from encrypted APFS volumes, which mount automatically exactly as before. I know Apple is pushing us to move to APFS, but with still no conversion for AppleRAID (I'm not keen to erase and restore a multiple terabyte volume just to switch), and no use for Time Machine which still doesn't support an APFS backup volume.

Is there a way to restore or securely emulate the previous behaviour such that the volumes are unlocked automatically for all users?

In case the specifics of my setup are useful; my startup volume is an APFS encrypted volume that only my admin account is authorised to unlock, but I use other, standard, user accounts (one for work, one for general use etc.) when actually using my system. I then have an AppleRAID volume of several disks using Core Storage encryption, and a CS encrypted Time Machine disk.

It appears to be a bug that was introduced in macOS 10.14.4. In this discussion some users report that the problem went away by itself, a recent poster found the problem was solved in the latest 10.14.5 beta, and others have resorted to using the third-party app AutoMounter.

In my case, I have a SD drive permanently inserted into the SD card reader. That worked perfectly for years. Since the update it would auto-mount only about 50% of all reboots.

Therefore, it seems your best bet will be to wait for macOS 10.14.5 and report the issue to Apple. Another thing that you could try is to delete and re-enter the passphrase in your Keychain Access.app. Concerning your comment, the necessary steps would be:

1. Open Keychain Access.app
2. Find the key by entering the volume's name in the search field
3. Select & delete the key
4. Open Disk Utility.app
5. Mount the volume in question and check the "Save passphrase" box
6. Go back to Keychain Access.app and locate the volume key again
7. Drag & drop they volume key into the "System" category in the left sidebar of Keychain Access.app. This step is necessary to enable auto-mounting.

P.S.: I experience another issue, which I suspect is related to this one. Possibly a new UUID is assigned to the drive which could be the reason it is not auto-mounted anymore.